Lap



June

R. GROETCHEN LAP Filed Feb. 27, 1935 y Y A A Y. r "I 'l l I //Hlllll g 'SQ L *r 1 f, I Y l 1 1- Y fi@ y I. VT? 1.5

Patented June 16, 1936 NITED STATES r OFFICE 2 Claims.

Other objects will appear from time to time in the specication and claims.

The invention is illustrated more or less diagrammatically in the laccompanying drawing, wherein:-

Figure 1 is a side elevation of the lap and mandrel, the lap being in position in a perforation;

Figure 2 is a transverse section taken at line 2 2 of Figure l on an enlarged scale;

Figure 3 is a side elevation' of the mandrel with the lap removed;

Figure 4 is a transverse section on an enlarged scale, taken at line 4 4 of Figure 3;

Figure 5 is a longitudinal section taken at line 5 5 of Figure 2, with the lap removed;

Like parts are designated by like characters throughout the specication and drawing.

I is a piece of material which has been perforated as at 2. 3 is any suitable rotating device by means of which the lap is to be rotated. 4 is the shaft of the mandrel. As indicated particularly in Figures 3 Iand 5, it is tapered at its lower end as at 5. Adjacent its lower end and lying partially on the untapered portion is a threaded section 6. A keyway 'I may be cut in the lower end of the shaft 4. As shown it extends from the lower end through the threaded section. At its lower end the member 4 is provided with a threaded cavity 8, extending inwardly from its bottom, within which may be positioned a screw 9 having an enlarged head Ill. A washer II is positioned about the screw and between the head I5 and the lower end of the member 4.

An interiorly threaded adjusting stop I2 is positioned upon the threaded portion 6 of the shaft 4. It may be provided with perforations I3 or any other suitable means by which it may be engaged by a tool so as to be rotated and thus adjusted along the shaft 4.

Positioned wholly or largely upon the tapered portion 5 of the shaft 4 is an expandible mandrel head I4. It is split, preferably from end to end, as at I5 and is provided adjacent its upper end with a laterally extending flange I6. It is provided interiorly with a plurality of inwardly extending and preferably generally radial vanes I1. One or more of these vanes, as for example the vane I3, may be provided with an inwardly extending key I9 to fit within the keyway l to prevent rotation of the mandrel head with respect to the shaft. The inner faces of the vanes I'I are preferably tapered as indicated in detail in Figure 5. At their lower ends the vanes are cut away as at 20 to provide shoul- 4ders 2l against which the washer II iits` as shown particularly in Figure 5.

Positioned about the outside of the mandrel head I4 is a flexible lap 22 which is preferably perforated by a series of perforations 23. The lap has an inwardly turned flange or edge 24, which lies within the slot I5 of the mandrel head I4. The lap is preferably made of some flexible and relatively soft material such as copper, and is given a spring shape so that it embraces the mandrel head closely and will conform to its size and shape, expanding as the head is expanded and contracting as it is contracted.

It will be realized that whereas I have herewith shown and described a practical operative device, nevertheless many changes might be made in the size, shape, number and disposition of parts without departing from the spirit of my invention and I wish, therefore, that my showing be taken as in a sense diagrammatic.

Particularly the material and shape of the lap might be almost infinitely varied and the invention is not limited to any particular type of lap member. Also the expandible mandrel head, while it is shown as made of a single piece having an end to end slot to permit ready expansion and contraction, might be made of other shapes, with one or more slots and they might or might not extend the full length of the mandrel head.

The use and operation of my invention are as follows:

The parts are assembled generally as shown in Figure 1. As illustrated in Figure 5 the adjustable mandrel head is shown in full lines, in approximately its uppermost position. To set the mandrel head for a given diameter the stop I2 is screwed up or down on the shaft 4 to the desired point. Then the screw 9 is screwed home and the washer on it, bearing against the shoulders 2| of the vanes II of the head I4, carries the head along the taper with the movement of the screw and so the head is moved along the taper until its upper end contacts the stop I2. ther movement is prevented by the stop.

To change the position of the head the stop I 2 may be moved upward and the screw 9 screwed further in, or else the screw 9 may be moved out and the stop rotated to move it downward. Thus the position of the expansible head I4 is determined by the position of the stop I2 and the screw 9. They determine the position and lock the head.

The lap itself is ilexible and preferably springy and is normally given an initial shape less in Furdiameter than the minimum diameter of the ad forced further up along the tapered portion' of` the shaft 4, the lap expands with it. AWhen it is reduced the lap contracts with'it.

The normal direction of rotation of the tool is indicated by the curved arrow in Figure 2. The edge of the lap carrying the inturned ,portion24 is the leading edge and the plain edge is the trailing edge.

With the parts assembled as shown in Figure 1 the tool as a whole is inserted in a perforation which is to be lapped, the desired lapping compound is put into the hole and the tool is rotated. In this manner the lapping operation isy carried out and any desired adjustment in the diameter of the lap is accomplished asY above indicated, by moving the adjustable mandrel head up or down along the tapered portion 5 of the'shaft 4.

adjustable stop, said mandrel head being split,

and hollowed to receive said screw and washer.

2. In a lapping device, a driving member constituting a mandrel shaft, said member being Vtapered and.- threaded at one end, and an interiorly tapered mandrel head positioned upon said tapered shaft', an adjustable stop on the shaft and means comprising a screw and a laterally extending washerrassociated therewith for drawing the mandrel head along the tapered portion and for holding it in contact with said adjustable stop, a ilexible metallic sleeve, having a flange thereon, constituting an operating member removably mounted upon said mandrel head, said mandrel head-being split, the ilange of said flexible metallic sleeve being positioned in the split in said mandrel head, said vsleeveY extending about the mandrel head throughout the major portion of its periphery, one end of the sleeve being freeto permit relative movement thereof with reference to the mandrel.

RICHARD GROETCI-IEN. 

